1. Field of the Invention
The present invention relates to tubular organic prostheses for permanent implantation within the body and the method for manufacturing the prostheses.
2. Description of the Prior Art
Tubular prostheses have been used for many years for the repair and replacement of hollow tubular organs. Vascular prostheses have been used to accomplish bypass operations and to repair damaged vessels in the body such as veins. Often, a piece of one's own vessel is taken from another part of the body to form the prosthesis. This involves putting the patient through an additional surgical procedure. In addition, in many patients, suitable vessels are not available.
Synthetic grafts were developed to overcome the above problems with the natural grafts. The grafts are made of woven fabric such as those illustrated in U.S. patent application Nos. 3,620,218 and 3,463,158 both issued to Schmitt, et al. The prior art fabric grafts encourage the initiation of tissue growth that partially blocks the grafts. In addition, at the ends of the grafts which are anastomosed to the recipient vessel, thrombosis may occur occluding the prosthesis. For these reasons, the prior art synthetic grafts are limited to diameters of 6 mm or larger. However, many patients require grafts for vessels smaller than 6 mm.
In U.S. Pat. No. 4,086,665 issued to Poirier, there is disclosed an artificial blood conduit consisting of a fabric tube surrounded by convolutions made of a silicon elastomer. Separate end connectors are provided for connecting to the vessels and organs. This conduit is for artificial hearts and blood pumps and is not well-suited for small vessel grafts of less than 6 mm in diameter.
Research in the manufacture of synthetic small blood vessel grafts is disclosed in an article entitled "A Sanguine Future for Biomaterials" in Science Magazine, Volume 217, Sept. 17, 1982. The article teaches surface coating of albumin on the conduit to reduce thrombogenicity. The article discloses conduits manufactured with long segments of polyether polyurethane which have a relatively high selectivity for the albumin. However, the use of albumin on the outer surface of the conduit will not reduce the thrombogenicity of the inner surface of the conduit that is in contact with the blood.
Furthermore, the connection between the prosthetic device and the tubular organ can cause problems. The ends of the tubular prostheses are generally sharp and may damage the live organ. U.S. Pat. No. 3,818,515 issued to Neville, discloses a bifurcated trachea prosthesis wherein the ends are tapered to facilitate entry into the appropriate vessel. One or more sleeves surround the ends of the device and are attached in a tongue and groove arrangement for suturing the device to the trachea. The sharp ends of the device may encourage infection and granulation tissue formation.
A method of connecting the ends of two tubular organs wherein one vessel is turned back over a connection device and the other vessel is pulled up over the turned back vessel, is disclosed in U.S. Pat. No. 3,774,615 issued to Lim et al. No means for suturing the vessels is disclosed.
Thus, there is a need for a synthetic tubular organic prosthesis having an inner surface and end connectors that will minimize neointimal hyperplasia, prevent thrombosis and permit the permanent implantation of the prosthesis in small blood vessels and other tubular organs.